In this study,investigators will recruit 100 DSM-Ⅴdefined EOS Han patients, older than 7 years old and onset of illness before 17 years old, and all EOS patients will receive a 8-week systematic olanzepine titration treatment and a battery of assessments of treatment effect and safety. Blood olanzepine plasma concentration will be tested regularly and genotyping of 8 polymorphisms of 5-HTR2A, DRD2 and COMT genes will be conducted by Polymerase Chain Reaction （PCR）, Restriction Fragment Length Polymorphism (RFLP) and TaqMan probes genotyping technology. The aim of the study is to explore the predictive factors on olanzepine treatment response in EOS, which can guide the individualized treatment and improve the cure rate of EOS in clinical setting.